Sulfur extraction process

ABSTRACT

SULFUR EXTRACTION FROM CRUSHED ORE, AS THE RESULT OF HEATING OF SAID ORE AS IT DESCENDS IN AN AREA OF HOT FLUID TO PRODUCE GLOBULES OF SAID SULFUR. THIS INVENTION RELATES TO A METHOD OF SEPARATING SULFUR FROM ORE AT GROUND LEVEL.

Jam. '19, 1971 J. H. BAILEY SULFUR EXTRACTION PROCESS FIQI.

ZONE A Filed May 20, 1969 INVENTOR JOHN H. BAILEY BY United States Patent 3,556,728 SULFUR EXTRACTION PROCESS John H. Bailey, Sulphur, La., assignor to Allied Chemical Corporation, New York, N.Y., a corporation of New York Filed May 20, 1969, Ser. No. 826,099 Int. C1. C01]: 17/08; B01d 9/00 U.S. Cl. 23308 7 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to a continuous process for recovering sulfur from sulfur bearing ore found at or brought to the surface. More specifically, sulfur is ex! tracted from ore deposits at or near the surface by placing said ore in a column containing fluid therein so as to move downwardly through said fluid, said fluid being heated in one area of said column to melt the sulfur. Heretofore known methods of extracting sulfur contained in low-grade ores found at or near the surface, for example washing crushed sulfur bearing ore in railroad cars with hot water to remove the sulfur have been expensive, time consuming, wasteful and therefore of peripheral utility. Such methods could not, in general, compete effectively with subsurface extraction processes employing Frasch-type techniques. A- further impractical feature of prior surface recovery techniques is the extent to which they rely on batch or semi-batch processing methods.

It has also been proposed to recover sulfur from crushed sulfur bearing ores by flowing them with concurrently flowing water under pressure through a conduit while subjecting them to heat to melt the sulfur. As in US. Pat. 2,537,842, issued Jan. 9, 1951, the melted sulfur, may then be quenched with cold water and globules or prills are formed. This technique has a number of disadvantages, however, relating, for example, to the pressure situation, the concurrently flowing water, the equipment and water requirement, and the size of the prills and their purity.

The present invention provides for a continuous flow of preheated, crushed, sulfur bearing ore to and through a relatively still or substantially counter-currently moving instream sulfur extraction fluid. More details and advantages of the present invention will become apparent upon examination of the following detailed disclosure.

SUMMARY OF THE INVENTION In accordance with the invention, crushed sulfur bearing ore, for example, crushed to a mesh size of 4, is moved by conventional means to a top of a column, for example, 200 feet high, depending on the temperature to be developed in the column, the length required in view of said temperature to keep the fluid in the column from flashing at the top thereof, the grind size of the ore originally introduced and the size sulfur globule sought to be recovered. The column is substantially filled with such fluid, for example, in the preferred embodiment, water. The water in a. lower middle section of the column is heated to a temperature of 290-320 F., by use of, for example, a hot water jacket surrounding said column at said section. The water above said section in the column may vary in temperature from about said temperature in Patented Jan. 19, 1971 "ice said previously mentioned section to about F, at the top thereof. Beneath said hot water section is cold Water, which is introduced at a point near the bottom of the hot water section and removed near the bottom of the column. The cold water section may have a temperature of from ambient to F., and usually 100 to 15 0 F. The column is open to the atmosphere at the top in the preferred embodiment.

According to the present invention, the crushed, sulfur bearing ore added to the column described above settles down the column to the bottom through the water. The sulfur in the ore is preheated in the first section and then melted from the ore in the hot water section previously described, which section has reached the sulfur melting temperature desired as the result of the application of heat to the column in the area of that section and the head of water thereabove allowing for the proper pressure conditions. As the sulfur melts, the droplets of sulfur coalesce to exclude almost all other foreign material, since sulfur exhibits a tendency to agglomerate excluding all impurities. The action of the water against the settling sulfur globules, that is the action of the friction of water in relation to the settling globules, results in a cleaning of the sulfur globules by the Water which further increases the purity thereof.

\As the droplets of globules of sulfur pass into the cold fluid zone, the droplets are quenched and form separate balls (rather than grouping together) of solid sulfur. All the material (spent ore and sulfur) is removed from the bottom of the column, separated, and the sulfur may be further purified, if desired. Without further purifying, however, by this method sulfur of a purity of as high as about 99 /2% may be anticipated.

In the preferred embodiment, as will be described hereinafter, the column is fllled with heated water from the bottom of the heated section to the top of the column. The water may be heated by the use of a jacket external to the column filled with, for example, hot oil. Alternatively, however, other heating means, including for example, the introduction of hot water at the bottom of the heated section and the withdrawal of the hot water from the top of the column, thus providing countercurrent flow of water with relation to descending crushed ore, is anticipated as an alternative. In any case, however, the movement of the hot water should either be relatively non-existent in the case when (1) no water is added to these heated water sections or where only a relatively minor make up water stream is added, or counter-current, (2) water is added to flow in a direction 0pposite to the movement of the incoming ore, as just described previously.

If water is added to move counter-currently to the descending ore, as described and removed at the top of the column to be recirculated, said water will be preferably treated before being reintroduced into the boiler for heating prior to introduction into the column to remove the sulfuric acid formed. Even where no flow of hot water in to the column is anticipated, as is true in the preferred embodiment, lime may be added to the column to neutralize the acid found in the column.

It is anticipated that at the bottom of the column the cold water will exit from one side of the column and the spent ore and sulfur globules will be collected at and removed from the bottom of the column.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows in FIGS. 1 and 2 two schematic embodiments for carrying out the invention.

DETAILED DESCRIPTION OF THE EMBODIMENT Crushed ore containing sulfur of say 4, is carried to the top of a separation column 2, that column being 3 filled with a hot fluid 3 for example, water. Said crushed ore with sulfur therein passes down through water in the first section 4 for preheating, which is in one embodiment, for example, 150 feet in height. The temperature in the preheat section 4 may extend from about the temperature at the top of the following hot water section to about for example, ambient at the top thereof. The crushed ore with sulfur passes from the preheat section into the hot water section 5, which is about 40 feet in height in this embodiment, said hot water being of the temperature of about 290320 F. At that temperature the sulfur melts and coalesces into globules as a result of its alfinity for itself and the wetting of the spent ore in comparison to the wetting of the sulfur. Section 5 of the tower 2 is heated, for example, by the use of a hot oil jacket surrounding the hot water section. The globules of sulfur passing down through the hot water are refined by their abrasive passage through the relatively still heated water to sulfur of high purity. Fines of ore become disattached from said prills, which move in a teardrop aerodynamic shape, during said passage. After passage through the hot water section 5, the prills of sulfur move into the cold water section 7 which in this embodiment is 10 feet in height, and are quenched. Adjacent the bottom of the hot water section, cold water, in the range of about ambient to 150 F., is introduced in section 7 through line 8. The cold water may be removed near the bottom of the cold water section, for example, line 9, filtered (if necessary) and recirculated through line 8, if desired. Ore and sulfur globules may exist through valved line 10 at the bottom of section 7. Alternatively (but not shown), ore may be flushed from the tower 7 through the outlet line 9 with the exiting cold water. After the ore and sulfur are flushed from the column, then the ore and sulfur globules (which may be up to 99 /2 purity) are separated by the use of, for example, screens of say 24 and then 48 mesh. The sulfur may then be further purified, if desired.

Deflection plates 13 (FIGURE 2) or other interrupting structure may be advantageously added to the column to slow down the descending movement of the ore and sulfur globules.

In FIGURE 2, the same embodiment for carrying out the invention is shown as in FIGURE 1, with the exception that instead of the hot jacket to provide heat to the column, hot water or steam of a temperature in the range necessary to raise the water to a sulfur melting temperature in the hot water section 5, marked area A in FIGURE 2, is introduced into the column through line 11. An equivalent amount of water is extracted from the column at line 12 to provide for counter-current fiow of the heated water to the flow of the descending ore and globules. Said extracted water through line 12 may be advantageously reheated and recirculated through line 11.

Of course, the flow of hot water shown in FIGURE 2 may be combined with the use of a jacket, as shown in FIGURE 1, if desired; and in any event it may be desired to allow for the introduction of some make up water.

The sulfur extraction process of this invention is highly practical as the result of low utilization of water, and recirculation of that water utilized, which is especially useful in arid regions where sulfur, especially shale deposits of sulfur may occur. Furthermore, the process is continuous without the use of moving parts. It is, furthermore, an extremely flexible process utilizing apparatus which may be easily changed to meet production needs, since the length of the water column and each section thereof may be varied to accomodate different sulfur bearing materials and different extraction time periods. In addition, if large prills of sulfur are desired or larger size crushed ore is used, lengthening of the heat section and the area of hot water before quenching will allow for more time for coalescence and the desired result. Such lengthening will also increase prill purity, because of a greater period of time for purifying descent of the prill.

A screening device near the end of the heated section, to force larger balls or prills of sulfur to form, may be added to the embodiment set forth, if desired. In addition, where desired, a closed column with a pressure valve at the top thereof may be substituted for the open column and the preheat section described above. How ever, it is considered extremely advantageous to use the open column described above since it is simple in construction and dispenses with all the cost, complications and danger of pressure equipment.

As mentioned previously, the fluid in the column might be other than water, for example, liquid calcium chloride. Where such other mediums are used, care must be taken to remove any contamination from the sulfur prills that may have been absorbed.

It is emphasized that the prills of sulfur as they settle through the column are separated from any impurities or fines by movement against the relatively still or countercurrently moving water or other mediums employed. The cleaning of the prill and purifying is thus in the present invention a function of the time it takes the prill to settle, the distance through which it settles, and the terpidity, that is the flow of the water and the prill in relation to each other.

While the present invention has been described in detail with respect to specific embodiments, it is intended that the applicant invention only be limited by the following claims.

I claim:

1. A method of separating sulfur from crushed ore using a standing column of water comprising the steps of providing a first zone in said column adjacent the top thereof of heated water below the temperature of the melting point of sulfur, introducing said ore into the top of the column into said first zone of said column to preheat said ore, providing a second zone of water in said column contiguous with and directly below said first mentioned zone wherein the temperature is such that sulfur melts and coalesces forming liquid sulfur droplets as it passes through said second zone, moving said ore under the action of gravity alone through said first zone and from said first zone directly by gravity alone into and through said second zone to melt the sulfur contained therein and form said droplets, said second zone being of sufficient height to provide for purifying and enlarging said droplets through further coalescence and movement therethrough under the action of gravity through said second zone, providing a third zone of cold water at a temperature below about F. in said column contiguous with and directly below said second zone by introducing cold water into said column in the upper portion of said third zone, moving said droplets under the action of gravity through said third zone to quench and thus solidify them into prills, removing an amount of water adjacent the bottom of said third zone equivalent to the amount of cold water introduced, and removing the prills and spent ore from the bottom end of said column.

2. A method as recited in claim 1, further comprising providing that the column be open to the atmosphere at the end at which the crushed ore is introduced thereinto, and removing the prills and the spent ore from the column at the end opposite from said open end.

3. The method as set forth in claim 2, the temperature of said second zone being about 280-340 F., and the temperature in said first zone ranging from that in the adjacent second zone to as low as ambient.

4. The method as set forth in claim 3, the temperature of said cold water being in the range of ambient to 150 F.

5. The method as set forth in claim 1, said hot water being in the temperature range of about 290320 F. in the sulfur melting zone.

6. The method as set forth in claim 3 further comprising introducing water near the end of the second zone and withdrawing a substantially equivalent amount of water near the point at which the crushed ore is introduced into the first zone.

7. The method as set forth in claim 3 further comprising introducing hot water near the end of the second zone and removing a substantially equivalent amount of hot water near the point at which the crushed ore is introduced into the first Zone.

I References Cited UNITED STATES PATENTS 2/ 1967 Lewis 23308X 3/1968 Skrzec 23229X FOREIGN PATENTS 1/ 1959 Pakistan 233 12 1/1955 Italy 23308 9/1954 Italy 23308 9/1943 Italy 23308 11/1932 Germany 23229 11/1965 Great Britain 23-229 NORMAN YUDKOFF, Primary Examiner S. J. EMERY, Assistant Examiner US. Cl. X.R. 

